Shear effects on solvated block copolymer lamellae: Polystyrene-polyisoprene in dioctyl phthalate

Abstract

Small-angle neutron scattering experiments were performed on a polystyrene-polyisoprene diblock copolymer in concentrated dioctyl phthalate solution under Couette shear. Lamellar orientations were monitored below and above the order-disorder transition temperature with the neutron beam incident either radially or tangentially on the cylindrical shear cell. It was found that lamellae are oriented mostly parallel to the plane of the shear cell walls. Oscillatory shear helps improve the lamellar alignment. Above the quiescent order-disorder transition, the shear-induced alignment (observed as an anisotropy of the scattering ring) follows a master curve for all temperatures.